To produce polyolefins, especially ethylene polymer or ethylene/α-olefin copolymer having a good impact strength and transparency, a metallocene catalyst system consisting of an organometallic compound (generally, metallocene) and an activator such as methylaluminoxane, wherein the organometallic compound has ligands such as cyclopentadienyl group, indenyl group, cycloheptadienyl group and fluorenyl group, which can control a stereoregularity and polymer molecular weight is disclosed in German Patent No. 3,007,725, U.S. Pat. Nos. 4,404,344, 4,874,880 and 5,324,800. Also, recently solid catalysts prepared by supporting both a metallocene compound and an activator into an inorganic carrier are disclosed in U.S. Pat. No. 4,808,561 and Korean Patent application No. 1998-44308. The non-uniform solid catalysts are capable of controlling the particle form of the polymer in the slurry or gas phase process. However, in the disclosed metallocene catalyst system, the catalysts are not obtained until various reaction steps are accompanied under complicated synthesis condition.
The supported solid catalysts used in gas phase and slurry process have to maintain a polymer of acceptable morphology and bulk density. In spite of the high activity characteristic of metallocene catalysts, polymer morphology and bulk density problems may result because the supported catalyst exhibits high activity in early duration when it is injected into reactor. This results in to rapid polymerization and severe fracturing of the catalyst particles leading to make the trouble to process operation.